django-rest-framework

What this skill does

# Django REST Framework

Master Django REST Framework for building robust, scalable RESTful
APIs with proper serialization and authentication.

## Serializers

Build type-safe data serialization with Django REST Framework serializers.

```python
from rest_framework import serializers
from django.contrib.auth.models import User

class UserSerializer(serializers.ModelSerializer):
    post_count = serializers.IntegerField(read_only=True)
    full_name = serializers.SerializerMethodField()

    class Meta:
        model = User
        fields = ['id', 'email', 'name', 'post_count', 'full_name']
        read_only_fields = ['id', 'created_at']
        extra_kwargs = {
            'email': {'required': True},
            'password': {'write_only': True}
        }

    def get_full_name(self, obj):
        return f"{obj.first_name} {obj.last_name}"

class PostSerializer(serializers.ModelSerializer):
    author = UserSerializer(read_only=True)
    author_id = serializers.IntegerField(write_only=True)

    class Meta:
        model = Post
        fields = '__all__'

    def validate_title(self, value):
        if len(value) < 5:
            raise serializers.ValidationError('Title must be at least 5 characters')
        return value

    def validate(self, data):
        if data.get('published') and not data.get('content'):
            raise serializers.ValidationError('Published posts must have content')
        return data

    def create(self, validated_data):
        # Custom creation logic
        post = Post.objects.create(**validated_data)
        # Send notification, etc.
        return post
```

## Custom Fields and Validation

Create custom serializer fields for complex data types.

```python
from rest_framework import serializers

class Base64ImageField(serializers.ImageField):
    """Handle base64 encoded images."""

    def to_internal_value(self, data):
        import base64
        from django.core.files.base import ContentFile

        if isinstance(data, str) and data.startswith('data:image'):
            format, imgstr = data.split(';base64,')
            ext = format.split('/')[-1]
            data = ContentFile(base64.b64decode(imgstr), name=f'temp.{ext}')

        return super().to_internal_value(data)

class PostSerializer(serializers.ModelSerializer):
    image = Base64ImageField(required=False)

    class Meta:
        model = Post
        fields = ['id', 'title', 'image']

# Custom validators
def validate_no_profanity(value):
    profanity_words = ['bad', 'worse']
    if any(word in value.lower() for word in profanity_words):
        raise serializers.ValidationError('Content contains profanity')
    return value

class CommentSerializer(serializers.ModelSerializer):
    content = serializers.CharField(validators=[validate_no_profanity])

    class Meta:
        model = Comment
        fields = ['id', 'content', 'created_at']
```

## Nested Serializers

Handle complex nested relationships.

```python
class CommentSerializer(serializers.ModelSerializer):
    author = UserSerializer(read_only=True)

    class Meta:
        model = Comment
        fields = ['id', 'content', 'author', 'created_at']

class PostSerializer(serializers.ModelSerializer):
    author = UserSerializer(read_only=True)
    comments = CommentSerializer(many=True, read_only=True)

    class Meta:
        model = Post
        fields = ['id', 'title', 'content', 'author', 'comments']

# Writable nested serializers
class PostCreateSerializer(serializers.ModelSerializer):
    comments = CommentSerializer(many=True, required=False)

    class Meta:
        model = Post
        fields = ['id', 'title', 'content', 'comments']

    def create(self, validated_data):
        comments_data = validated_data.pop('comments', [])
        post = Post.objects.create(**validated_data)

        for comment_data in comments_data:
            Comment.objects.create(post=post, **comment_data)

        return post

# Dynamic nested serialization
class PostSerializer(serializers.ModelSerializer):
    class Meta:
        model = Post
        fields = ['id', 'title', 'content']

    def __init__(self, *args, **kwargs):
        include_comments = kwargs.pop('include_comments', False)
        super().__init__(*args, **kwargs)

        if include_comments:
            self.fields['comments'] = CommentSerializer(many=True, read_only=True)
```

## ViewSets

Create RESTful endpoints with ViewSets.

```python
from rest_framework import viewsets, permissions, status
from rest_framework.decorators import action
from rest_framework.response import Response

class PostViewSet(viewsets.ModelViewSet):
    queryset = Post.objects.all()
    serializer_class = PostSerializer
    permission_classes = [permissions.IsAuthenticatedOrReadOnly]
    filterset_fields = ['author', 'published']
    search_fields = ['title', 'content']
    ordering_fields = ['created_at', 'title']

    def get_queryset(self):
        queryset = super().get_queryset()
        if self.action == 'list':
            queryset = queryset.filter(published=True)
        return queryset.select_related('author').prefetch_related('comments')

    def get_serializer_class(self):
        if self.action == 'create':
            return PostCreateSerializer
        return PostSerializer

    def perform_create(self, serializer):
        serializer.save(author=self.request.user)

    @action(detail=True, methods=['post'])
    def publish(self, request, pk=None):
        post = self.get_object()
        post.published = True
        post.save()
        return Response({'status': 'published'})

    @action(detail=False, methods=['get'])
    def recent(self, request):
        recent_posts = self.get_queryset()[:10]
        serializer = self.get_serializer(recent_posts, many=True)
        return Response(serializer.data)

# ReadOnly ViewSet
class CategoryViewSet(viewsets.ReadOnlyModelViewSet):
    queryset = Category.objects.all()
    serializer_class = CategorySerializer
```

## Routers

Configure URL routing for ViewSets.

```python
from rest_framework.routers import DefaultRouter, SimpleRouter
from django.urls import path, include

# Default router (with API root view)
router = DefaultRouter()
router.register(r'posts', PostViewSet, basename='post')
router.register(r'users', UserViewSet, basename='user')
router.register(r'comments', CommentViewSet, basename='comment')

urlpatterns = [
    path('api/', include(router.urls)),
]

# Simple router (no API root)
simple_router = SimpleRouter()
simple_router.register(r'posts', PostViewSet)

# Custom routing
from rest_framework.routers import Route, DynamicRoute

class CustomRouter(DefaultRouter):
    routes = [
        Route(
            url=r'^{prefix}/$',
            mapping={'get': 'list', 'post': 'create'},
            name='{basename}-list',
            detail=False,
            initkwargs={}
        ),
        # Add custom routes
    ]
```

## Permissions

Implement authentication and authorization.

```python
from rest_framework import permissions

class IsAuthorOrReadOnly(permissions.BasePermission):
    """Custom permission to only allow authors to edit."""

    def has_object_permission(self, request, view, obj):
        # Read permissions for any request
        if request.method in permissions.SAFE_METHODS:
            return True

        # Write permissions only for author
        return obj.author == request.user

class IsOwnerOrAdmin(permissions.BasePermission):
    def has_object_permission(self, request, view, obj):
        return obj.owner == request.user or request.user.is_staff

# Usage in ViewSet
class PostViewSet(viewsets.ModelViewSet):
    queryset = Post.objects.all()
    serializer_class = PostSerializer
    permission_classes = [permissions.IsAuthenticated, IsAuthorOrReadOnly]

# Multiple permission classes
from rest_framework.permissions import IsAuthenticated, IsAdminUser

class AdminPostViewSet(viewsets.ModelViewSet):
    queryset = Post.objects.all()
    serializer_class = PostSer